The gardeners dictionary

The 1733 edition of The gardeners dictionary includes an entry on tanner’s bark:

TAN or TANNERS BARK, is the Bark of the Oak-tree, chopped and ground into coarse Powder, to be used in Tanning or Dressing of Skins; after which it is of great Use in Gardening: First, by its Fermentation (when laid in a Body), which is always moderate, and of a long Duration, which renders it of great Service to Hot-beds. . . . A Hot-bed well prepared with this Tan, will continue a moderate Heat upward of six Months, and there being very little Steam arising from it, in comparison to Horse-dung, renders it much better for the Growth of all Sorts of Plants; and when the Heat begins to decay, if the Tan be fresh stirred up, and a little new added to it, it will heat again and continue some Months longer.